The invention relates to two-cycle internal combustion engines and, more particularly, to crankcase scavenged, two-cycle internal combustion engines which include a generally vertically extending crankshaft and employ engine drains to lubricate crankshaft bearings.
In crankcase scavenged, two-cycle internal combustion engines, a mixture of fuel and lubricate or so-called engine "drains" accumulating in one or more low points or sumps in the crankcase commonly are employed to lubricate the crankshaft bearings. The "drains" typically are transferred from the low point(s) or sump(s) to the upper crankshaft bearing by a suction action created by the engine intake manifold vacuum. For engines having lower intake manifold vacuums and/or "taller" crankcases, the intake manifold vacuum may not be sufficient to overcome the head between the sump and upper and provide adequate upward flow of the "drains" to the upper bearing during all engine operating conditions.
Attention is directed to the following United States patents relating to internal combustion engines including systems for recylcing "drains":
______________________________________ Patentee Pat. No. Issue Date ______________________________________ Irgens st al. 1,606,424 November 9, 1926 Aikman 2,128,065 August 23, 1938 Jensen 2,936,748 May 17,1960 Janeway et al. 2,959,164 November 8, 1960 Dalrymple 2,983,334 May 9, 1961 Heidner 3,132,635 May 12, 1964 Fenton 3,523,592 August 11, 1970 Brown 3,730,149 May 1, 1973 Resnick et al. 3,805,751 April 23, 1974 King 3,811,806 May 21, 1974 Turner et al. 3,859,967 January 14, 1975 Hackbarth 3,911,870 October 14, 1975 Turner 3,929,111 December 30, 1975 Turner 4,121,551 October 24, 1978 ______________________________________